Thermal gradient-driven skyrmion dynamics with suppressed skyrmion Hall angle

Abstract

Thermal-gradient-driven skyrmion dynamics offers a promising route to green spintronics, enabling the utilization of waste heat by information transport and processing. Using micromagnetic simulations, we investigate Néel skyrmions in a Co/Pt bilayer nanoracetrack and demonstrate that stochastic torques induced by a thermal gradient drive skyrmion motion toward the hotter region with a nearly vanishing Hall angle. Skyrmion dynamics depends sensitively on intrinsic material parameters: velocity decreases with increasing damping constant (α), increases with stronger thermal gradients, and varies systematically with saturation magnetization (Ms), strength of interfacial Dzyaloshinskii-Moriya interaction (DMI) (Dint), and uniaxial out-of-plane anisotropy (Ku). In this work, we identify a specific range of material parameters and geometrical parameters of racetracks within which the skyrmion Hall angle due to thermally driven skyrmions remains strongly suppressed by nearly 20% less than that for electrically (spin-transfer torque) driven skyrmions. This comprehensive, geometrical, and material parameter-dependent study establishes a universal design framework for minimizing the skyrmion Hall effect in thermal-gradient-driven spintronic systems. In the second section, we investigate skyrmion dynamics driven by hybrid torques arising from the combined action of an electrical spin-transfer torque and a Joule-heating-induced temperature gradient. The skyrmion velocity and Hall angle reveal two distinct dynamical regimes separated by a critical electrical current density. These results demonstrate that the dominant torque governs both the longitudinal motion and the skyrmion Hall response.